Circular Strain Gauges
Ideal for hole, Bolt and Hoop Strain Measurement
A circular strain gauge is designed to measure strain distributed around a central point typically around holes, bolts, shafts, and stress concentrations. At MFL Strain Gauges (based in N.Ireland), our circular gauges are engineered to capture complex radial and circumferential (hoop) strain fields in a compact, easy to install format, helping you understand how loads are transferred around critical features. Usual resistance requirements range between 120Ω - 2,000Ω (Ohms). MFL can custom design and manufacture to your exact requirements. We also have thousands of Strain Gauges in STOCK ready to ship in a range of sizes with NEXT DAY DELIVERY within UK & IRELAND.
What is a circular strain gauge?
Unlike a linear strain gauge that measures strain along one axis, a circular strain gauge uses one or more foil grids arranged in a ring or segment around a reference point or opening.
Ring shaped or segment layout
The foil grid follows a circular path to sense strain around a hole, bolt circle, or shaft. This is ideal where stress is not purely axial and varies around the circumference.
Measures hoop (circumferential) and radial effects
Circular gauges are particularly effective for measuring hoop strain common in pipes, pressure vessels, flanges, and cylindrical shells as well as strain around fastener holes and cut outs.
Precision foil on flexible polyimide backing
MFL circular strain gauges use precision etched foil on a thin polyimide backing, keeping the gauge stable and easy to bond to both flat and curved surfaces.
The result is a compact sensor that effectively “wraps around” the area of interest, making complex local stress patterns easier to quantify.
Typical applications for circular strain gauges
1) Stress around holes, cut-outs, and notches (stress concentrations)
Circular gauges are ideal for evaluating local stress concentration:
Around bolt holes in flanges, brackets, and structural joints
Around service openings and access holes in plates and shells
Around notches and geometric discontinuities in fatigue critical components
Measuring strain around the feature helps verify local stress levels and supports fatigue and safety assessments.
2) Flanges, bolted joints, and gasketed connections
In flanged connections, load distribution is crucial:
Monitoring strain around bolt circles on pipe flanges and vessel nozzles
Evaluating how bolt preload and internal pressure combine in service
Supporting gasket seating checks and joint integrity verification
Circular gauges provide a useful “average” view of how load is shared around the joint.
3) Shafts, hubs, and rotating components
Circular gauges can be applied to rotating parts to study combined loading effects:
Measuring hoop strain on rotating discs or hubs under centrifugal load
Assessing stress around keyways, splines, or cross drilled holes
Instrumenting brake discs, flywheels, and similar components for R&D
They help engineers understand how speed, torque, and thermal effects interact in critical rotating parts.
4) Pressure vessels, pipes, and cylindrical shells (hoop strain)
For thin walled pressure containing components, hoop strain is often the key parameter:
Monitoring local strain around nozzles and manways in pressure vessels
Assessing reinforcement effectiveness around openings in tanks and shells
Studying local stress fields in pipes at branch connections or supports
Circular gauges help quantify the combined effects of internal pressure, external loads, and local geometry.
5) Experimental mechanics and research
In test labs and universities, circular gauges support detailed stress analysis:
Investigating stress concentration factors around different hole shapes and patterns
Validating numerical models of local stress fields
Studying fatigue initiation at stress raisers
Options and customisation with MFL Circular Gauges
To suit different geometries, installation constraints, and environments, MFL circular strain gauges are available with:
A range of grid sizes to suit different hole diameters and strain gradients
Multiple resistance options to match your instrumentation requirements
Different lead styles for routing and connection preferences
Optional encapsulation when additional protection is needed for handling or harsh environments
If you share the feature size (hole/bolt circle/shaft), material, and loading type, we can recommend a suitable circular gauge configuration.
Why choose MFL Strain Gauges for circular gauges?
As a N.Ireland-based foil strain gauge manufacturer, MFL designs circular gauges to provide:
Accurate, repeatable measurement around holes, bolts, and curved features
Robust foil patterns for demanding industrial and research applications
Thin, flexible polyimide backing, with encapsulation available where required
Configurable grid sizes, resistance values, and lead styles to match your setup
Whether you’re analysing stress around bolt holes, monitoring a flanged joint, or instrumenting rotating discs, MFL circular strain gauges provide a practical, high quality solution for capturing complex local strain fields.
Circular strain gauge FAQs
What does a circular strain gauge measure?
Circular gauges measure strain distributed around a central feature, commonly hoop (circumferential) strain and strain around holes and cut-outs.
Are circular gauges suitable for pipes and pressure vessels?
Yes—circular gauges are often used where hoop strain is important, including pipes, flanges, and pressure containing components.
Do you offer different sizes, resistance values, and lead styles?
Yes—MFL offers a range of grid sizes, resistance options, and lead styles, with encapsulation available when required.
Need help selecting a circular gauge?
Contact MFL Strain Gauges with your feature size, material, surface curvature, and environment and we’ll recommend a suitable configuration.